Blades of the abovementioned type of modern turbines or compressors, for example compressor moving blades, are provided with coatings which have to be renewed after a certain period of operation. To renew the coating, the blades have to be demounted from the turbine or the compressor. The demounting of such compressor moving blades must take place manually on account of the many different activities to be performed and is comparatively time-consuming. During the time when a blade is being demounted, work cannot be carried out at other points on a rotor of the respective turbine or compressor, such as, for example, in the region of the combustion chhub.
It is therefore common practice for the rotor to be destacked in order to recoat its blades and for the blades of the turbine or compressor then either to be recoated in the bladed blade wheels or to be demounted from the wheel disks and newly coated individually.
U.S. Pat. No. 6,416,286 discloses two devices which assist the installation of the last blade of a moving blade ring. The blades are designed as shroud blades and are pushed individually into axial holding grooves of a rotor disk. Since the shrouds are of Z-shaped design, as seen in the radial direction, it is not possible for the last moving blade to be pushed axially into the otherwise fully equipped moving blade ring. The last turbine blade of the moving blade ring therefore has to be introduced radially (without a moving blade root) on account of the shroud. In order to make this possible, the approximately closed shroud ring is spread both in the axial direction and in the tangential direction, that is to say circumferential direction. For this purpose, U.S. Pat. No. 6,416,286 proposes spreading the gap of the open shroud ring by means of a first device comprising two threaded rods, clamps and screw nuts, thus leading to sufficient play in the circumferential direction. A second device, which acts with force upon the moving blade roots of the adjacent moving blades, with respect to the last moving blade, axially in the opposite direction, brings about a sufficient play in the axial direction in the shroud ring, so that the last moving blade of the moving blade ring can be inserted radially and its shroud closes the shroud ring. The last moving blade of the ring can subsequently be fastened to the rotor disk by a separately produced moving blade root being pushed in axially.
Moreover, DE 100 20 229 A1 shows a method and a device for demounting a turbine blade. The turbine blade is pushed in in an axial holding groove. Between the groove bottom of the holding groove and the moving blade root of the turbine blade, there is a mounting gap, into which a hooked slide can be pushed. The hooked slide is provided with projections or hooks which are shaped correspondingly to cooling air supply ports located on the blade root on the groove bottom side. After the hooked slide has been pushed into the gap and the projections lie opposite the cooling air supply ports, a supporting slide is additionally pushed in between the groove bottom and hooked slide, lifts the hooked slide and thus hooks the hooks together with the cooling air supply ports of the blade root. Subsequently, by the hooked slide being drawn out, the moving blade can be drawn out of the holding groove with the aid of hydraulics.